feat: Introduce ITValuePublisher interface and refactor indicators for event-driven value updates.

lib/core/tseries/ITValuePublisher.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace QuanTAlib;
+
+/// <summary>
+/// Interface for objects that publish TValue updates.
+/// </summary>
+public interface ITValuePublisher
+{
+    /// <summary>
+    /// Event triggered when a new TValue is available.
+    /// </summary>
+    event Action<TValue> Pub;
+}